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From: guerby@gnat.com (Laurent Guerby)
Subject: Re: overload ":=" ???
Date: 1996/07/22
Message-ID: <ws97mrvsot6.fsf@schonberg.cs.nyu.edu>#1/1
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sender: guerby@schonberg.cs.nyu.edu
references: <dewar.837740729@schonberg> <4soh73$56h@newsbf02.news.aol.com>
organization: New York University
reply-to: guerby@gnat.com
newsgroups: comp.lang.ada
Date: 1996-07-22T00:00:00+00:00
List-Id: <comp.lang.ada>


Laurent> This "sort of string" is built in Ada 95 under the name
Laurent> Bounded_String.

David> I looked at that, and it would be great, but...  RM A.04.04.106
David> seems to say that this isn't good with dynamic pointers (or am
David> I misreading this?)

   First, here is the GNAT implementation of Bounded_String:

   private

      type Bounded_String is record
         Length : Length_Range := 0;
         Data   : String (1 .. Max_Length);
      end record;

   So I guess it's very close to what you want, with a big bonus, all
Ada 95 String handling routines are waiting to be used. Note that
you'll need to instanciate a generic to use it.

   Second, A.4.4(106) is an "implementation advice" which states:

RM>			       Implementation Advice
RM>
RM> 106   Bounded string objects should not be implemented by implicit pointers
RM> and dynamic allocation.

   As far as I understand it, it advices (not requires) compiler
writers not to use a pointer and "new" to implement this type (this
kind of stuff is for Unbounded_Strings). This is not at all a concern
to the user, who sees only "type Bounded_String is private".

David> what about "write-ability" ????

   Please define "write-ability" (I don't want to assume it's related
to the number of characters to type ;-).

David> This signature will self-destruct in 10 seconds...

   Boom ;-).

-- 
Laurent Guerby <guerby@gnat.com>, Team Ada.
   "Use the Source, Luke. The Source will be with you, always (GPL)."